Keto Diet and losing weight too fast

I'm 1 week into a 6 week Keto diet structured with 1.5g protein per lb with equal amount of calories from fat. This equlas 375g protein and 167g fat a day from my starting weight of 252lbs. Diet has not been the issue, I do not feel too hungry (someone doesn't feel hungry on a diet isn't really dieting, right?). Nor have I suffered any loss in strength (yet).

My concern is that I am losing weight too fast. I dropped 8lbs of water in the first 48 hours (252 to 244 no concern here as I tend to carry excess water) and have lost an additional 4lbs (240 now) over the next 4 days. My starting BF was around 16-17% and I haven't measured it since I started the diet.

As I understand it my first carb up day should be 2 weeks into the diet, with carbing up once every week thereafter. Should I include a carb up day tomorrow (7 days into the Keto) or not? Also has anyone else experienced weight loss this fast on a keto diet and what were their results with respect to their strength and retaining muscle mass?

It can take 3-4 days for some people to get into ketosis so im not too sure what might have been going down in those first 48 hrs but it was most likely not anywhere near full swing yet or lost weight from ketosis.

12 pounds in 6 days is pretty extreme. On a side note you can go to walmart and pick up keto stix...they will tell you if your in ketosis or not.